Special value text in spinboxes is not automatically selected on mouse focus

If a spin box is showing its special value text, a user that attempts to focus on the spin box with a mouse click will be unable to make any changes to the contents without first selecting the whole special value text.

Tab focus selects the entire contents, and this is convenient- it would be good if mouse focus does the same if special value text is being displayed. 

See attached example: changing focus from one spin box to the other using the mouse requires more than one click to modify the contents.